1. Field of the Invention
The present invention relates to an electronic device including an electronic element and a base member which are electrically coupled through bumps. The electronic device can be suitably used for a sensor device for detecting a dynamic quantity such as angular velocity and acceleration, for example.
2. Description of the Related Art
Conventionally, an electronic device used for a sensor device includes a sensor chip having a movable part on one surface thereof, and a circuit chip as a base member. For example, the sensor device includes an angular velocity sensor, an acceleration sensor, and a pressure sensor, each having a sensor chip in which the movable part as a detecting part displaces in accordance with a dynamic quantity such as acceleration, angular velocity, and pressure applied thereto.
For example, US 2006/0097331 A1 (corresponding to JP-2006-189418 A) discloses a sensor device which includes a sensor chip having a movable part on one surface thereof, a circuit chip arranged to face the one surface of the sensor chip, and bumps located between the sensor chip and the circuit chip.
In the sensor device, the sensor chip and the circuit chip are electrically coupled through the bumps. Thereby, a coupling part between the sensor chip and the circuit chip is restricted from deforming due to an impact, compared with a case where the sensor chip and the circuit chip are electrically coupled through wires. Thus, a change of a parasitic capacity at the coupling part is restricted.
Furthermore, this semiconductor device includes an adhesive film having an electric insulation property. The adhesive film is attached to the one surface of the sensor chip while a portion of the adhesive film corresponding to the movable part is separated from the movable part so that a hollow part is provided between the adhesive film and the movable part.
For example, the hollow part is provided by forming a concave part in the adhesive film so that the adhesive film is separated from the movable part. Thereby, the adhesive film can cover the movable part without restricting a movement of the movable part.
In addition, in manufacturing this semiconductor device, the adhesive film having the hollow part is attached to the one surface of the sensor chip, then, the sensor chip faces the circuit chip through the bumps, and the bumps are bonded to the sensor chip and the circuit chip by thermo-compression bonding or ultrasonic bonding, for example.
In this method, the bumps are bonded to the sensor chip and the circuit chip after the adhesive film is attached to the sensor chip. Thus, the hollow part of the adhesive film may be deformed due to a viscosity reduction of the adhesive film by heating, or a vibration during the ultrasonic bonding.
When the hollow part is deformed, the adhesive film may touch the movable part, and may restrict the movement of the movable part. This problem may occur in any other sensor devices which include a sensor chip having a movable part on one surface, and a circuit chip facing the one surface of the sensor chip through bumps so that the sensor chip and the circuit chip are separated from each other by the bumps.
Thus, when an adhesive film is attached to the one surface of the sensor chip while a portion of the adhesive film corresponding to the movable part is separated from the movable part so that a hollow part is provided between the adhesive film and the movable part, the hollow part may be deformed by heating or vibration during bonding of the bumps.